• 한국제4기학회:학술대회논문집
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• 한국제4기학회 2004년도 하계학술대회
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• pp.29-29
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• 2004

Long term observational analysis by climatologists has confirmedthat the global warming is no longer a topic of debate among scientists andpolicy makers. According to the report of IPCC-2001 (Intergovernmental Panelon Climate Change), the global mean surface air temperature is increasinggradually. The reported increase of mean temperature is by 0.6 degree in the end of twentieth century. This could represent severe threat for propertylosses especially due to increase in the number of extreme weather arising out of global warming. period of model integration from 2001 to 2100 using output of ECHAM4/HOPE-G of Max Planet Institute of Meteorology (MPI) for IPCC SRES (Special Report on Emission Scenarios). The main results of this study indicate increase of surface air temperature by 6.20C and precipitation by 2.6% over Korea in the end of 21st century. Simulation results also show that there is increase in daily maximum and minimum temperatures while decrease in diurnal temperature range (DTR). DTR changes are diminished mainly due to relatively rapid increase of daily minimum temperature than that of daily maximumtemperature. It has been observed that increase in precipitation amount anddecrease in the number of rainy days lead to increase of pre precipitationintensity.

• The Korean Journal of Ecology
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• 제16권2호
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• pp.155-157
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• 1993

The life-cycle and seasonal abundance of Anaulaciulus koreanus koreanus was studied at Hwang-dong, Chonbuk Province, Korea from October 1990 to February 1992. The egg hatches in spring and the pupoid stage is passed through within the egg shell. The juvenile develops as far as stadium IX by the third year following the birth. Pairing and oviposition take place in the fourth year spring when females are at stadium XI. They seem to live one or two years more after egg-laying. Anamorphosis was observed in this species. Abundance of A. koreanus koreSanus increases from April to May when there appears thefirst peak. It fals gradualy thereafter and the species spends summer months underground from July to September. The second peak appears in October and the activity decreases again in November getting ready to overwinter. The first peak arises from a large number of individuals of 2 and 3 year old overwintered plus newly hatched spring juveniles, and the second from 1 to 3 years old wanderings. Inactivity observed in the species during summer and winter seasons appears to be a temporal due to the extreme temperatures.

• Journal of Biosystems Engineering
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• 제40권4호
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• pp.335-344
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• 2015

Purpose: Soybean growth is adversely affected by environmental stresses such as drought, extreme temperatures, and nutrient deficiency. The objective of this study was to develop a method for rapid measurement of drought stress in soybean plants using a hyperspectral fluorescence imaging technique. Methods: Hyperspectral fluorescence images were obtained using UV-A light with 365 nm excitation. Two soybean cultivars under drought stress were analyzed. A partial least square regression (PLSR) model was used to predict drought stress in soybeans. Results: Partial least square (PLS) images were obtained for the two soybean cultivars using the results of the developed model during the period of drought stress treatment. Analysis of the PLS images showed that the accuracy of drought stress discrimination in the two cultivars was 0.973 for an 8-day treatment group and 0.969 for a 6-day treatment group. Conclusions: These results validate the use of hyperspectral fluorescence images for assessing drought stress in soybeans.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.2036-2041
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• 2014

In this paper, a thermal model is developed for the bus bar system to predict the temperature variation during the transient time period and to calculate both the steady-state and transient electrical current carrying capacity (ampacity) of bus bar. The bus bar system installed in the power house of Kumaraguru College of Technology, Coimbatore has been considered. Temperature variation predicted in the modelling is validated by observing the current and steady state temperatures in different feeders of the bus bar. Magnetic field of the extreme phases R and B induces more current in the middle phase Y. Hence, the steady state temperature in the phase Y is greater than other two phases. The transient capabilities of the bus bar are illustrated by calculating the variations in the bus bar temperature when it is subjected to a step change in current during the peak hours due to increase in hostel utilities and facilities (5.30 pm to 10.30 pm). The physical and geometrical properties of the bus bar and temperature variation in the bus bar are used to estimate the thermal time constants for common bus bar cross-sections. An analytical expression for the time constant of the bus bar is derived.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 추계 학술논문 발표대회
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• pp.211-212
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• 2011

It was very important to evaluate concrete experimentally at elevated temperature because concrete was filled with aggregate of concrete volume about 70 percent. Concrete exposure to high temperatures produces changes in its internal structure, for instance loss of its strength and deformation capacity, in extreme cases risking the service life of the structure. The work of this paper is performed to evaluate the thermal behavior of ultra-high strength concrete having different water to cement ratio (strength), fine aggregate to aggregate ratio and maximum size of coarse aggregate. For exposure to 500℃ during 1 hour, residual mechanical properties of the ultra-high strength concrete decreased as the s/a ratio decreases and the maximum size of coarse aggregate increases.

• 천문학회지
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• 제42권6호
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• pp.145-153
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• 2009

We present measurements of diffuse interstellar $H_2$ absorption lines in the continuum spectra of 10 early-type stars. The data were observed with the Berkeley Extreme and Far-Ultraviolet Spectrometer (BEFS) of the ORFEUS telescope on board the ORFEUS-SPAS I and II space-shuttle missions in 1993 and 1996, respectively. The spectra extend from the interstellar cutoff at 912 $\AA$ to about 1200 $\AA$ with a resolution of ~ 3000 and statistical signal-to-noise ratios between 10 and 65. Adopting Doppler broadening velocities from high-resolution optical observations, we obtain the $H_2$ column densities of rotational levels J" = 0 through 5 for each line of sight. The kinetic temperatures derived from J" = 0 and 1 states show a small variation around the mean value of 80 K, except for the component toward HD 219188, which has a temperature of 211 K. Based on a synthetic interstellar cloud model described in our previous work, we derive the incident UV intensity IUV and the hydrogen density $n_H$ of the observed components to be -0.4 $\leq$ log $I_{UV}\leq2.2$ and $6.3{\leq}n_H2500cm^{-3}$, respectively.

• Journal of Welding and Joining
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• 제32권3호
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• pp.89-94
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• 2014

AISI 304 austenitic stainless steel is widely used for LNG pipes for LNG transmission thanks to its good metallurgical and mechanical properties. In the present research, impact toughness of a gas tungsten arc welded AISI 304 stainless steel pipe was evaluated between room and liquid nitrogen ($-196^{\circ}C$) test temperatures. In addition, a comparative study was made of the fracture behavior of FCC crystal structured stainless steel weldments and BCC crystal structured mild steels(A-grade and SS400). The results showed a slight decrease in the impact energy of the AISI 304 base metal, heat affected zone(HAZ), and welded zone with decreasing test temperature. In addition, the welded metal has the highest absorbed impact energy, followed by HAZ and the base metal.

• 천문학논총
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• 제20권1호
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• pp.11-20
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• 2005

We present measurements of interstellar $H_2$ absorption lines in the continuum spectra of 54 early-type stars in the Galactic disk and halo and 3 stars in the Magellanic Clouds. The data were obtained with the Berkeley Extreme and Far-Ultraviolet Spectrometer (BEFS), part of the ORFEUS telescope, which flew on the ORFEUS-SPAS I and II space-shuttle missions in 1993 and 1996, respectively. The spectra extend from the interstellar cutoff at $912{\AA}$ to about $1200{\AA}$ with a spectral resolution of ${\sim}3000$ and statistical signal-to-noise ratios between 10 and 65. Assuming a velocity profile derived from optical observations (when available), we model the column densities N(J) of the rotational levels J = 0 through 5 for each line of sight. Our data reproduce the relationships among molecular and total hydrogen column density, fractional molecular abundance, and reddening first seen in Copernicusobservations of nearby stars (Savage et al. 1977). The results show that most of these molecular clouds have $H_2$ total column densities between $10^{15}cm^{-2}$ and $10^{21}cm^{-2}$, and kinetic temperatures from 21 K to 232 K, with average of 89 K, consistent with the result of Copernicus (Savage et al. 1977).

• 한국재료학회지
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• 제27권10호
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• pp.552-556
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• 2017

Evaluation of the durability and stability of materials used in power plants is of great importance because parts or components for turbines, heat exchangers and compressors are often exposed to extreme environments such as high temperature and pressure. In this work, high-temperature corrosion behavior of 316 L stainless steel in a carbon dioxide environment was studied to examine the applicability of a material for a supercritical carbon dioxide Brayton cycle as the next generation power plant system. The specimens were exposed in a high-purity carbon dioxide environment at temperatures ranging from 500 to $800^{\circ}C$ during 1000 hours. The features of the corroded products were examined by optical microscope and scanning electron microscope, and the chemical compound was determined by x-ray photoelectron spectroscopy. The results show that while the 316 L stainless steel had good corrosion resistance in the range of $500-700^{\circ}C$ in the carbon dioxide environment, the corrosion resistance at $800^{\circ}C$ was very poor due to chipping the corroded products off, which resulted in a considerable loss in weight.

• Asian Journal of Atmospheric Environment
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• 제8권2호
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• pp.96-107
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• 2014

Extreme recovery of the thermal energy from the combustion of flue gas may bring about early gas condensation resulting in the increased formation of nitric acid vapor. The behavior of the nitric acid formed inside the stack and in the atmosphere was investigated through a computer-aided simulation in this study. Low temperatures led to high conversion rates of the nitrogen oxide to nitric acid, according to the Arrhenius relationship. Larger acid plumes could be formed with the cooled flue gas at $40^{\circ}C$ than the present exiting gas at $115^{\circ}C$. The acid vapor plume of 0.1 ppm extended to 25 m wide and 200 m high. The wind, which had a seasonal local average of 3 m/s, expanded the influencing area to 170 m along the ground level. Its tail stretched 50 m longer at $40^{\circ}C$ than at $115^{\circ}C$. The emission concentration of the acid vapor in the summer season was a little lower than in the winter. However, a warm atmosphere facilitated the Brownian motion of the discharged flue gas, finally leading to more vigorous dispersion.